- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Electrical and optical properties of heavily Ge-Doped AlGaN
摘要： We report the effect of germanium as n-type dopant on the electrical and optical properties of AlxGa1-xN layers grown by plasma-assisted molecular-beam epitaxy. The Al content has been varied from x = 0 to 0.66, confirmed by Rutherford backscattering spectrometry, and the Ge concentration was increased up to [Ge] = 1×1021 cm?3. Even at these high doping levels (> 1% atomic fraction) Ge does not induce any structural degradation in AlGaN layers with x < 0.15. However, for higher Al compositions, clustering of Ge forming crystallites were observed. Hall effect measurements show a gradual decrease of the carrier concentration when increasing the Al mole fraction, which is already noticeable in samples with x = 0.24. Samples with x = 0.64-0.66 remain conductive (σ = 0.8-0.3 Ω?1cm?1), but the donor activation rate drops to around 0.1% (carrier concentration around 1×1018 cm?3 for [Ge] ≈ 1×1021 cm?3). From the optical point of view, the low temperature photoluminescence is dominated by the band-to-band emission, which show only spectral shift and broadening associated to the Burstein-Moss effect. The evolution of the photoluminescence peak position with temperature shows that the free carriers due to Ge doping can efficiently screen the potential fluctuations induced by alloy disorder.
关键词： germanium doping,molecular-beam epitaxy,optical properties,AlGaN,electrical properties
更新于2025-09-19 17:15:36
-
Halogen-free GeO <sub/>2</sub> conversion: electrochemical reduction <i>vs.</i> complexation in (DTBC) <sub/>2</sub> Ge[Py(CN) <sub/>n</sub> ] ( <i>n</i> = 0…2) complexes
摘要： Halogen-free GeO2 conversion: electrochemical reduction vs. complexation in (DTBC)2Ge[Py(CN)n] (n = 0…2) complexes?
关键词： halogen-free conversion,germanium,catecholate complexes,electrochemical reduction,DFT calculations
更新于2025-09-19 17:15:36
-
Characterization of the chips generated by the nanomachining of germanium for X-ray crystal optics
摘要： Micro-Raman spectroscopy, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were used to study the effect of cutting speed and cutting depth on the mode of the single-point diamond fly cutting of Ge(110) surface via crystallinity of the chips. Reducing the cutting depth from 15 to 2 μm and concurrently cutting speed from 10 to 2 mm/min at 2000 rpm, the content of amorphous phase in the chips increased at the expense of the crystalline one from 28 to 46%. Simultaneously, the chip morphology visible by SEM suggested transition from a brittle to a mixed brittle-ductile mode of nanomachining. The damage transition line indicates 1/3 portion of the ductile component at 2-μm cutting depth that produced twisted lamellae of a width of 18–20 μm without any signs of a fracture. As the feed rate here was 1 μm/rev, the tool made 18–20 revolutions while passing the same point of the nanomachined surface that was enough to gradually remove the surface region damaged by the brittle cutting component along with the entire amorphous region beneath, both being delaminated by the chips. This explains the dislocation-free single-crystal lattice beneath the Ge(110) surface machined under these conditions. A close relationship between the brittle mode of nanomachining and crystallinity of the chips observed by micro-Raman spectroscopy and SEM was confirmed by HR-TEM showing dense occurrence of nanocrystals in the chips coming from the nanomachinings with 5-μm and 15-μm cutting depths. These results demonstrate potential of the single-point diamond machining for the preparation of high-quality X-ray surfaces with undistorted single-crystal lattice beneath for next-generation X-ray crystal optics.
关键词： Micro-Raman spectroscopy,X-ray crystal optics,Scanning electron microscopy,Germanium,Transmission electron microscopy,Single-point diamond machining
更新于2025-09-19 17:15:36
-
Shallow and Undoped Germanium Quantum Wells: A Playground for Spin and Hybrid Quantum Technology
摘要： Buried-channel semiconductor heterostructures are an archetype material platform for the fabrication of gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface; however, nearby surface states degrade the electrical properties of the starting material. Here, a 2D hole gas of high mobility (5 × 10^5 cm^2 V^{-1} s^{-1}) is demonstrated in a very shallow strained germanium (Ge) channel, which is located only 22 nm below the surface. The top-gate of a dopant-less field effect transistor controls the channel carrier density confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The high mobility leads to mean free paths ≈ 6 μm, setting new benchmarks for holes in shallow field effect transistors. The high mobility, along with a percolation density of 1.2 × 10^{11} cm^{-2}, light effective mass (0.09m_e), and high effective g-factor (up to 9.2) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies.
关键词： germanium,quantum well,quantum devices,mobility
更新于2025-09-19 17:15:36
-
Nonstoichiometric amorphous silicon carbide films as promising antireflection and protective coatings for germanium in IR spectral range
摘要： A technology for preparation of amorphous nonstoichiometric hydrogenated silicon carbide (a-SixC1-x:H) films using the PE-CVD method has been developed. Such films with refractive index n = 1.8–2.1 are suitable to obtain antireflection effect on germanium in the IR spectral region. Single- and two-sided antireflection coatings of Ge enabled to increase its optical transmission up to 65% and 96% in the maximum transmission, respectively. The obtained films have good mechanical properties (H > 12 GPa, E = 100 GPa). Presence of Si-C bonds in the a-SixC1-x:H films restricts their range of application to the spectral interval 2.5–10 μm. The prepared films are uniform in composition and have high adhesion to the substrate. Variation of deposition conditions makes it possible to obtain a-SixC1-x:H films having high hardness and Young's modulus. High deposition rate, optimal optical properties of the a-SixC1-x:H films and good combination of mechanical properties for the Ge/a-SixC1-x:H film structures make them to be promising for practical application as antireflection and protective coatings for germanium.
关键词： Germanium,Antireflection coatings,Elements of IR optics,Nonstoichiometric SiC films
更新于2025-09-19 17:15:36
-
aSi:H/i-aSi:H/p+aSiGe:H Graded Band Gap Single Junction Solar Cell
摘要： In this paper, we present a single junction graded band gap thin film solar cell using heavily phosphorous doped amorphous silicon, intrinsic amorphous silicon and heavily boron doped amorphous silicon germanium. The first part of the work presents a rigorous analysis of J-V characteristics of recommended photovoltaic structure under short circuit (SC), open circuit (OC), dark and AM 1.5G illumination standard. Further, optimisation of thickness of active layers of the suggested n+aSi:H/i aSi:H/p+aSiGe:H solar cell structure is done using SCAPS1D solar simulator. The active layer thickness of the proposed solar cell is 430 nm only. Low active layer thickness and absence of multiple junctions reduces the material requirement, complexity and cost of the proposed solar cell. Furthermore, fabrication of individual layers and overall summary of their characterisation have been done. Finally, the proposed structure has been fabricated and validated its J-V characteristics. The fabricated solar cell has short circuit current density (Jsc) of 11.67 mA/cm2, open circuit voltage (Voc) of 1.18 V, fill factor (FF) of 0.857 and conversion efficiency (η) of 11.80 % which is on par with other announced single junction amorphous silicon solar cells. Here, we are reporting a single junction graded band gap solar cell using combination of aSi:H and aSiGe:H alloys with varying doping levels for the first time, which is better in conversion efficiency while compact and light.
关键词： SCAPS1D,graded bandgap,amorphous silicon germanium,J-V characteristics,PECVD,Amorphous Silicon Alloys
更新于2025-09-19 17:13:59
-
N-type doping of Ge by P spin on dopant and pulsed laser melting
摘要： N-type doping of Ge based on spin on dopant sources and pulsed laser melting has been proposed as an alternative to the use of complex and expensive techniques such as ion-implantation or molecular beam epitaxy. Optimization of the n+/p junction has been carried out with a KrF laser (of 22 ns pulse duration) by studying the effect of different laser fluences and the number of pulses. The diffusion profiles, sheet resistance, carrier density and mobility have been determined by secondary ion mass spectrometry and Van der Pauw–Hall measurements. By properly selecting the range of laser energy density and number of pulses, a high level of activation (>1019 cm?3) with good mobility (350–450 cm2 V?1 s?1) and low sheet resistance (<50 Ω/,) has been achieved. In addition, the good crystalline quality of the samples has been confirmed by high-resolution x-ray diffraction measurements, demonstrating the viability of such a low-cost manufacturing process for next generation Ge-based devices.
关键词： germanium,spin on dopant,phosphorus doping,semiconductors,pulsed laser melting
更新于2025-09-19 17:13:59
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Germanium Photodetectors with 60-nm Absorption Coverage Extension and ～2× Quantum Efficiency Enhancement across L-Band
摘要： Germanium-on-insulator (GOI) metal-semiconductor-metal (MSM) photodetectors were demonstrated with a 60 nm extension on the absorption coverage and a ~2× enhancement on the quantum efficiency across the L-band.
关键词： germanium,longer wavelength detection,photodetectors,silicon nitride stressor,CMOS-compatible
更新于2025-09-16 10:30:52
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - High-Speed Germanium Pin Photodiodes Integrated on Silicon-on-Insulator Nanophotonic Waveguides
摘要： Hetero-structured silicon-germanium-silicon photodetectors operating under low-reverse-voltages with high responsivity, fast response, and low dark-current levels are reported. A bit-error-rate of 10-9 is experimentally achieved for conventional data rates of 10, 20, and 25 Gbps, providing optical power sensitivities of -13.9, -12.7, and -11.3 dBm.
关键词： silicon-on-insulator,complementary metal-oxide-semiconductor technology,silicon nanophotonics,germanium,optical photodetectors
更新于2025-09-16 10:30:52
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Coupled-Resonator-Induced-Transparency on Germanium-on-Insulator Mid-Infrared Platform
摘要： We demonstrate the operation of a thermally tunable coupled-resonator-induced transparency system on a germanium-on-insulator photonic platform working at a mid-infrared wavelength of approximately 1.95 μm. A maximum coupling rate of 1.25 GHz is realized between the two evanescently coupled microring resonators.
关键词： Thermo-optic tuning,Mid-infrared,Microring resonators,Germanium-on-insulator
更新于2025-09-16 10:30:52